The graphic above shows U.S. revenue for Flurry’s portable gaming category- a category that now includes Nintendo DS, Sony PSP, iOS, and Android. As you can see, iOS and Android have together taken the lead from Nintendo with 58% of revenues in comparison to last year’s 34%. In comparison, Nintendo DS held 57% during 2010, while dropping to just 36% in 2011. Total US revenue jumped from $2.7 billion in 2009 to $3.3 billion in 2011.

When comparing combined game revenues of the two veterans– Sony and Nintendo– with the combined revenues of the two new guys– Apple and Google– 2011 will be the first year where the emerging platforms dominate with iOS and Android estimated to take in $1.9 billion in comparison to the DS and PSP’s $1.4 billion. That accounts for a $200 million drop for Sony and Nintendo and $1.1 billion increase for iOS and Android from 2010. Perhaps investors were right to urge Nintendo to begin developing iOS titles.

As for Nintendo, the company who captured approximately two-thirds of the market in 2009 has seen their “enemy of the future” demote them to just a third of the market. Sony clearly has some catching up to do, but is hard at work on highly anticipated new handheld devices for 2012.

So what is Nintendo and Sony missing? Well 500,000+ low-priced and often free apps certainly wouldn’t hurt, as Flurry notes, “the days of paying $25, or more, for a cartridge at a retail store may soon end”. There’s no debate about whether or not Sony and Nintendo have to gear their mobile strategies towards what Apple is doing, and with the rumors of iTV on the horizon, they may soon have much more to worry about than just their mobile businesses.